This may be a bit tangential to the topic under discussion, but I was struck by Ueshiba's reference to his sword method in quote #1 from The Secret Teachings of Aikido i.e. 合気神髄:All the gods of Japan gathered and brought aiki truly into life, fostering universal spirit and sho chiku bai swordsmanship. The double-edged sword of heaven and earth was manifest; that sword symbolizes the spiritual movement that works to purge the world of filth and corruption. 日本中神々現れて 合気の出現を寿ぎたまり。大和魂の錬成、松竹海の剣法、天地合体して両刃の剣、精神の発動によって世の濁りを洗う。

So what struck me is his use of "Sho Chiku Bai no Kenpo" (松竹海［梅?］の剣法）as this is the name Shirata used for his ken teachings and is the first time I have ever heard the phrase in reference to Ueshiba.

As far as we know the name was also used by Hikitsuchi for the ken and is used by Shin Kage ryu (and for sake), but it is striking to see it used by Ueshiba especially in reference to some sort of divine transmission. I am wondering if there is some more specific meaning or reference here. And are you aware of any other references that might clear up why this name is used in reference to swordwork connected to Ueshiba?